Process for obtaining transparent effects on regenerated cellulose fibers



Patented May 2, 1950 BROGESS: FGBL OBTAINING TRANSPARENT v EEFEG'IIS N-REGENERA'TED CELLULOSE f FIBERS "Paul Walter Stcinlin; Basel,Switzerland; assignor Aktiengesellschaft Cilander, Herisau, Swit- 1zenlandi 1N0 Drawing; Application J uly.31,,194'6; Serial No..(587;5-10: In- Switzerland 'Aprii2'2, 1943 7' Claims 1.

The present application is irr the nature ot a continuation in part asmyrearlier copendingi'appl'ication Serial Nol 5233;7882 mean/raw 2; 1944, now abandoned.

Transparent fabrics; alsm known: as. organdi'es, have as a rule beenmadefrompurecotton-materials, in particular: muslin, or, more rarely;voile or other finefabrics, suchcambric, etc. Or

gandies of especially" fine quality were made of natural silk.

The process hereafter described relates to the production of plain orpatternem smooth:orcrepe transparent fabrics trormmaterialsconsisti'ngof staplefibre made from regenerated cellulose alone or ofstaple fibre madefrom: regenerated cellulose and cotton, or o'i' mixedcotton and staple fibre made" from regenerated'rcellulosexVariousexperiments were maderin: the past to transform textiles of this1 hind by theordinary methods used for' cotton 'fabrl'cs. However. evenby varying and. adapting working conditions; such as concentrationoi'acidsrand alkaline: swell ihg agents, and the duration: oftheproceduradt proved impossib e: to turn out marketablevgoo ds. Indeed thematerials hithertoproduced were horny, brittle and stiffened. and" in noway. suited forpractical use. The-presentrproc'ess, on the; contrary,produces: transparent. fabrics: which perfectly satisfy a llrecuirementsas to: appearance, lustre, softness ami durabilitv; and'zshow a highdegreeaoftranscarency combined with aremarkable clearness of weave.

These effects are ohtainediby first treating the fabric with strong, hotalkali, then s b ec ing it to the action of strong, preferably-coldsulphuric acid, and finally again treating it with strong alka i thistime cold. The fabric can, eventually, be subjected to a treatmentwithalkaline or acid swelling agents either before or after.

The process is suited for fabrics made ofjpure stapletflbre made" fromregenerated cellulose, or woven with cotton andstapleflbre made. from.re.- generated cellulose, and also'i'orthcse woven. with mixedstaplefiber madeifromunegenerateacellu lose and cotton yarn. Naturally,materials in which any or all of the above-combinations are present,either in plain crpattern weave, including "of course applications:wittr'embroideryor Swiss dotted. weave, canalso he .treatedi'bwmyprocess.

It is advantageous to delubricate and bleach the fabric to be processed.Crude fabrics can, however, be treated in the same way. In thisconnection it should be borne in mind that, ac-

cording to theinventiomthis processing issuitable for use in any phaseof pre treatment.

. My process can be usedto advantage in ccmbirnation with treatment byswelling agents; order and manner in which these treatmentsr are applieddepend on the result desired.

In some cases afurther improvement can be achieved by repeating theprocess wholly orin part.

Treatment with strong sulphuric acid ls-carried out with sulphuric acidof. -52 B. atitemperatures ranging. from --5 to +2(l C. for-"at least 5seconds.

Treatment with strong, cold alkali is carried out withan alkali of atleast 15 B15. attemperatures: ranging from -59 to +25 0. forat least- 5seconds.

By hot alkali is understood. a treatment acp cording to the presentprocess withhotalkall solution of mercerizing strength, at atempera.-ture of. 25 C. or over, havingadurationof. 5%sec. ends or more.

It is. advantageous to rinse. and neutralize be;- tween acid and alkaineswelling treatments. Between two consecutive alkaline treatments the.question of rinsing and neutralizing.isdecided bythetype ofefiectdesired,

Patterned as well as p ain transparent fabrics can be obta ned with thepresent. processibyap plying suitable. reserves beforethe swellingtreatment. For example imago'effectscanbe achieved. by printing withpigments, resulting. in opaque. non-transparent patterns, By this.methodit. is. possible, according to the type of process chosen to. usepigment carriers proof against acid. and. alkaline swellingagents, suchas gums or artificial resins, whichresult in local opaque .efiects ornon-acidproof thickening agents which produce stifiened. transparentdesigns in which the efiect of contrast is. due to the pigmentation.alone; It is moreover possible to introduce reservesflduriii any phaseof the. transforming processso asto. achievaior example, a. transfaarentefi'ectami then, by rinsing and subsequent. swelling and. shrinking,obtain the. appearance of. crepe. Itiis also possibleto. getintermediary .effectsfby'the. imprint of. swelling agents, and.subsequent treatment with hot. alkali; The reserves-can even; he.applied during various phases of the. process in such away that thetransformed material shows untreated and swollen, that is shrunken andtransparent areas one next to the other.

It is evident that by printing in colours or by the usenf colouredreserves such efifects can be obtained in various tints.

Fabrics submitted. to the present process can be dyed either before orafter treatment. In this way, according to the method of procedure, themost varied results can be obtained, such as plain transparent, or,according to the different aflinity for the dye caused by differentlocal treatment, shaded effects.

My process may be illustrated by means of a single example:

A singed, bleached and tentered fabric made from staple fibre made fromregenerated cellulose is treated with NaOH of 30 Be. at 50 C. for 8seconds, rinsed, neutralized and dried. It is then subjected to theaction of sulphuric acid of 45 B. at 15 C. for 7 seconds, neutralizedand rinsed. Next comes a treatment with NaOH of 31.B. at 10 C. for 6seconds. After neutralizing, rinsing and finishing in the usual way, avery fine staple fibre transparent fabric is obtained.

I claim:

. :1. A multiple step process for obtaining transparent effects upon afabric consisting predominantly of regenerated cellulose staple fiberscom-' prising treating said fabric with hot caustic soda of meroerizingstrength at temperatures of the order of 50 C. for at least seconds butnot subst'antialiy more than 5 seconds, then treating said fabric withsulfuric acid of 40 to 52 Baum at a temperature ranging from- 5 to 20 C.for a period of time of the order of 5 to 7 seconds, and then treatingsaid fabric with caustic soda of mercerizing strength at temperatures of5 to 25 C. for at least 5 seconds but not substantially more than 5seconds.

, 2. A multiple step process for obtaining trans parent effects upon afabric consisting predominantly of regenerated cellulose staple fiberscomprising treating said fabric with hot caustic soda of mercerizingstrength at temperatures of the order of 50 C. for at least 5 secondsbut not substantially more than 5 seconds, removing free caustic sodafrom the fabric, then treating said fabric with sulfuric acid of 40 to52 Baum at a temperature ranging from 5 to 20 C. for a period of time ofthe order of 5 to 7 seconds, and then treating said fabric with causticsoda of mercerizing strength at temperatures of 5 to 25 C. for at least5 seconds but not substantially more than 5 seconds.

3. A multiple step process for obtaining transparenteffects upon afabric consisting predominantly of regenerated cellulose staple fiberscomprising treating said fabric with hot caustic soda of mercerizingstrength at temperatures of the order of 50 C. for at least 5 secondsbut not substantially more than 5 seconds, then treating said fabricwith sulfuric acid of 40 to 52 Baum at a temperature ranging from 5 to20 C. for a period of time of the order of 5 to 7 seconds, removing freesulfuric acid from the fabric, and then treating said fabric withcaustic soda of mercerizing strength at temperatures of 5 to 25 C. forat least 5 seconds but not substantially more than 5 seconds.

' 4. A multiple step process for obtaining transparent effects upon afabric consisting predominantly of regenerated cellulose staple fiberscomprising treating said fabric with hot caustic soda of mercerizingstrength at temperatures of the order of 50 C. for at least 5 secondsbut not sub stantially more than 5 seconds, washing and drying thefabric, then treating said fabric with sulfuric acid of 40 to 52 Baum ata temperature ranging from 5 to 20 C. for a period of time of the orderof 5. to 7 seconds, and then treating said fabric with caustic soda ofmercerizing strength at temperatures of -5 to 25 C. for at least 5seconds but not substantially more than 5 seconds.

5. A multiple stepprocess for obtaining transparent effects upon afabric consisting predominantly of regenerated cellulose staple fiberscomprising treating said fabric with hot caustic soda of mercerizingstrength at temperatures of the order of 50 C. for at least 5 secondsbut not substantially more than 5 seconds, then treating said fabricwith sulfuric acid of 40 to 52 Baum at a temperature ranging from 5 to20 C. for a period of time of the order of 5 to 7 seconds, washing anddrying the fabric, and then treating said fabric with caustic soda ofmercerizing strength at temperatures of -5 to 25 C. for at least 5seconds but not substantially more than 5 seconds.

6. A multiple step process for obtaining transparent effects upon afabric consisting predomi-' nantly of regenerated cellulose staplefibers comprising treating said fabric with caustic soda of the order of30 Baum at a. temperature of the order of 50 C. for a period of time ofthe order of 5 to 8 seconds, then treating said fabric withsulfuric'acid of the order of Baum at a temperature of the order of 15C. for a period of time of the order of 7 seconds, and then treatingsaid fabric with caustic soda of the order of 31 Baum at a, temperatureof the order of 10 C. for a period of time of the order of 6 seconds.

7. A multiple step process for obtaining transparent effects upon afabric consisting predominantly of regenerated cellulose staple fiberscomprising treating said fabric with caustic soda of the order of 30Baum at a temperature of the order of C. for a period of time of theorder of 8 seconds, rinsing, neutralizing, and drying the fabric, thentreating said fabric with sulfuric acid of the order of 45 Baum at atemperature of the order of 15 C. for a'period of time of the order of'7 seconds, neutralizing and rinsing the fabric,-

and then'treating said fabric with caustic soda of the order of 31 Baumat a temperature of the order of 10 C. for a of 6 seconds.

PAUL WALTER STEINLIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS period of time of the order Italy Mar. 11, 1936

1. A MULTIPLE STEP PROCESS FOR OBTAINING TRANSPARENT EFFECTS UPON AFABRIC CONSISTING PREDOMINANTLY OF REGENERATED CELLULOSE STAPLE FIBERSCOMPRISING TREATING SAID FABRIC WITH HOT CAUSTIC SODA OF MERCERIZINGSTRENGTH AT TEMPERATURES OF THE ORDER OF 50*C. FOR AT LEAST 5 SECONDSBUT NOT SUBSTANTIALLY MORE THAN 5 SECONDS, THEN TREATING SAID FABRICWITH SULFURIC ACID OF 40* TO 52* BAUME AT A TEMPERATURE RANGING FROM -5*TO 20*C. FOR A PERIOD OF TIME OF THE ORDER OF 5 TO 7 SECONDS, AND THENTREATING SAID FABRIC WITH CAUSTIC SODA OF MERCERIZING STRENGTH ATTEMPERATURES OF -5* TO 25*C. FOR AT LEAST 5 SECONDS BUT NOTSUBSTANTIALLY MORE THAN 5 SECONDS.